Pancreatic islets of Langerhans are the only organ of insulin production in the body. However, they have a limited capacity for regeneration. This limited regeneration capacity predisposes mammals to develop diabetes mellitus. Islet neogenesis associated protein (INGAP, SEQ ID NO: 2) plays a role in stimulation of islet neogenesis, in particular, in beta cell regeneration from ductal cells. INGAP104-118 peptide (IGLHDPSHGTLPNGS, SEQ ID NO: 1), a 15-amino acid peptide comprising amino acids 104–118 of the INGAP protein, is biologically active and is capable of inducing islet cell regeneration in an animal model. Pharmaceutical compositions containing a mammalian INGAP104-118 peptide can be used for treatment of endocrine pancreatic insufficiency which may result from diabetes mellitus.
Antibodies to INGAP104-118 peptide may be generated in patients following repeated dosing of INGAP104-118 peptide or may be generated as autoantibodies to the endogenous protein, which may mitigate the action of INGAP or serve as a diagnostic marker for diabetes. Thus, there is a need in the art for a convenient assay for detecting antibodies that may be raised in a subject following treatment with INGAP104-118 peptide.